Coating composition



166. COMPOSITIONS.

f Exa i COATING PLASTIC. or r/ a T r a. We

Patented Jan. 11, 1927.

- UNITED STATES ALBERT FERDINAND LINDSTROM, OF NUTLEY, NEW JERSEY,ASSIGNOR TO WESTING- HOUSE LAMP COMPANY, A CORPORATION OF PENNSYLVANIA.

COATING COMPOSITION.

No Drawing? An object of my invention is to provide a paint orpreparation for producin certain effects in substances when appliedthereto.

Another object is the provision of a coating composition which, whenapplied to such ob]ects as electric lamps, lamp fixtures and the like,will permit such devices to operate with a minimum of absorption of thelight and a maximum diffusion.

Other objects will be apparent from a reading of the followindescription.

Efforts have been ma e in the past toward producing an opalescenteffect, similar to that of the pearl with its dull lustre, particularlyin illumination engineering. Such an efi'ect is very pleasing andartistic, especially when obtained in connetztion with a strong lightwhich it is desired to subdue without sacrificing, to any great extent,the intensit of the light rays. Various methods and contrivances havebeen used for accomplishing the end sought, many 'of which are uitefamiliar to the users of electricity for ighting purposes.

is a glass composition, commonly termed rugal glass, in which gryoliteis employed to tain the desired effect. en glass of 'that character isemployed in shades, globes .and, particularly, electric lamp bulbs, itis to be noted that the difiused light emitted is of low and unequalintensity which is probably due to the light absorption bein very highand, furthermore, because such a sorption is not uniform. Again, afteran electric lamp, having a bulb made of opal glass, has been burned ashort time there is a tendency for the glass to decompose and give offgases, as SiF,) silicon fluoride, which is injurious to the filament ofthe lamp and shortens its life. The further disadvantage in employing anopaque lass in the bulbs of electric lamps lies in t 1e manufacture ofsuch lamps. In the manufacture of an electric lamp, it is necessary toalign the interior structure, termed the mount, in proper relation withrespect to the light center. Obviously, unless the bulb is made oftransparent or translucent material, such operligrnove greaseoF-"dir Oneof these Application filed September 23, 1921 Serial No. 502,789.

ation cannot be done with any degree of accuracy.

I have discovered that the objects of the invention may be attained andthat the disa advantages resulting from the use of opal glass may beavoided by providing a com-. position of matter or preparationcontaining certain constituents which, when applied as a coating, alterthe light rays in proper proportion and intensity, to provide formaximum diffusion with minimum absorption.

More specifically stated, the invention resides in the production of areparation composed of a of such nature that its effect on some of thelight rays prevents their passage to a more or less extent, that is, itis more or less opaque; a fill made up of particles more or less transucent; and a binder 1 for uniting the pigment and filler together and toany object to which the enamel or paint may be applied. 7

In addition to the foregoing properties, it is desirable that thecoating composition, especially when employed as a superficial coatingfor electric lamp bulbs, be of such nature that itiiscsubstantiallywaterproof or impervious to wateggto the etxent that itmay be cleansed,as bv washingpnwiping to 7 Furthermore, the coatin composition, when aplied to an object, s ould set into a smoot even coating.

withstan ing'a temperature of about 400 0. without blisterin or chippingoff. This latter is essential ecause the temperature of an electric lampincreases considerably with burning. Inasmuch as electric lamps arefrequently exposed to the atmos here, it is a requisite of suchcomposition t at the constituents of the atmosphere shall have noinfluence thereon.

Another (property it should possess is that of The best results may besecured if the pjgg Furthermore, if it is more or a (mas with thebinder. A further desirable feature is to have it more or lesstranslucent. The smoothness of the coating is greatly-enhanced by theselection of a pigment and a filler having a fine degree ofcomminut-ion. The binder employed should have the proper specificgravity so that, when mixed with the other ingredients, the mixture willbe of the right consistency to render its application to an object orsubstance comparatively easy. It should also serve to firmly hold thepigment and filler together and to any body to which it may be applied,and should have the additional property of setting, upon the applicationof heat, into a compact, hard and homogeneous mass.

The opalescent effect produced is subject to variations, depending to aconsiderable extent upon the proportions employed and the manner inwhich the composition is applied, together with the thickness of thecoating. The most pleasing effect is obtfllled if thefpiipportionsarebapproximatel 5 1S. 0 t e pligment, a out 100 gms. 0 the iiller andsu stantlally 700 cc. of a solution ol the having a specific gravity ofabout 1.2. By altering the quantities of the different ingredients,considerable variation in lighting effects may be produced. Forinstance, if a greater quantity of filler is employed, the coating willbe more in the nature of frosting, whereas, if the quantity of pigmentis increased, the coating will have a chalky appearance, and the smoothfinish secured by the binder will be destroyed. Variations of thethickness of the coating results in corresponding changes in theintensity of the light. It is believed, however, that, when theproportions are correct, variations in the thickness of the coating willnot destroy the opalescenteffect but will merely subdue or increase it,depending, of course, upon whether it is thick or thin.

It is desirable that the specific gravit of the aqueous solution of thebinder shal approximate fairly closely that mentioned above, because, ifthe mixture be very viscous, the paint will blister when the lamp isburned. If an alkali binder be used, the alkali content should not betoo great, otherwise blooming or blisters, resulting from combination ofthe excess alkali with the carbon-dioxide of the atmosphere, wouldapear. p A mixture which I have employed and found to meet all therequirements may be as follows, the proportions and materials statedbeing merely illustrative of one form of coating composition which willproduce the desired efiects.

As a pigment, I prefer to use tin oxide in the finest grade obtainable.8cm grams of this substance is used in making up the batch. One hundredgrams of a filler of an a ueous solution of an alkaline silicatepreteraqily sodium silicate, having a specilic gravityof 1.180. About400 cc. of the hind-- er are employed. This mixture is placed in amixing vessel and thoroughly agitated until a homogeneous mixture isobtained. The articles or substances to be coated are either sprayedwith or dipped into the enamel and thereafter subjected to heattreatment at an elevated temperature of about 125 to 200 C. forapproximately two minutes. This latter step sets the enamel and causesthe pigment and filler to be firmly united to each other as well as tothe body to which the paint has been applied, and, at the same time,makes the paint resistant to disintegrating influences, as heat,moisture, etc. If it is desired to further increase the resistanceproperties of the coating, it may be sprayed with a 30% solution ofammonium chloride and baked for an additiontal two minutes. The articlemay then be washed and dried.

The foregoing method is more fully described and claimed in thecopending a plication of Hageman and Schmid, erial #431,587, filedDecember 18, 1920, forpaint and process of applying the same, and ofHageman and Lindstrom, Serial #461,379, filed April 14, 1921, for aprocess of coating materials, each of which is assigned to theWestinghouse Lamp Company.

Modifications of the foregoing com sition and its application maysuggest t emselves to those skilled in the art, but such as fall withinthe scope of the appended claims are contemplated by my invention.

What is claimed is:

1. A coating composition for producing opalescent efi'ects comprisingtin oxide a filler of translucent material and a bin er.

2. A coating composition for producing opalescent effects comprising anintimate mixture of tin oxide in a finely divided state, kaolin in afinely divided stateand sodium silicate. n

3. A paint comprising tin oxide, kaolin rising approximately. 100 I .115and sodium silicate, in such proportions as, to produce an opalescentefiect when applied 3 iOO. COMPOSITIONS, V Examind COATING OR PLASTIC. fv

6. A paint composition ada ted for coattin oxide and a filler of veryfinely divided 1 ing objects to impart a pear y eifect,.c0m-' white andsubstantially translucent mateprising a pigment consisting essentiallyof rial, and a binder for uniting the pigment tin oxide and a filler ofa finely divided and filler into an integral mass when sub- 5translucent material and a binder in which jected to heat.

the said pigment and filler are insoluble. In testimony whereof, I havehereunto 15 7 A paint composition adapted for coatsubscribed my nameSeptember 22, 1921. ing objects to produce opalescent effects comprisinga pigment consisting essentially of ALBERT FERDINAND LINDSTROM-

